This invention relates to systems and processes for cleaning, chemical sterilizing or disinfecting medical devices. More specifically, this invention relates to method and apparatus for reducing or eliminating the occlusion of medical devices with the support in the container during the process of cleaning, sterilizing, or disinfecting.
Medical instruments have traditionally been sterilized or disinfected using either heat such as is provided by steam, or a chemical in liquid, gas, or vapor state. Prior to sterilization or disinfection, the instruments to be treated are usually first cleaned and then sterilized or disinfected. After sterilization or disinfection with a liquid chemical germicide, purified water is used to rinse the instruments and then the instruments are dried. Numerous publications regarding the cleaning of medical devices and the sterilizing of medical devices are available.
U.S. Pat. No. 5,443,801 discloses a transportable cleaning/sterilizing apparatus and method for inside-outside washing and sterilization of medical/dental instruments. The apparatus functions in four sequential cycles: wash, rinse, sterilize, and dry. The sterilization step is conducted using ozonated and purified water, and the drying step is accomplished by injecting ozonated/deozonated sterile warm dry oxygen, or sterile inert gas into and exhausted from the wash chamber under a positive pressure relative to atmospheric. In this process, the device has to be rinsed with purified water after it is sterilized to remove sterilant residue before drying step.
U.S. Pat. No. 5,505,218 to Steinhauser et al. discloses a device for cleaning, disinfecting and maintaining medical or dental instruments. The device has a pot-shaped container with a multiplicity of mountings in the interior of the container each for one of tool holder, a water supply system, a compressed air supply system, and an ultrasonic transducer. The disinfection is conducted with heated water, and the drying is conducted with hot compressed air. This system is not designed for sterilization.
U.S. Pat. No. 5,279,799 to Moser et al. discloses apparatus for cleaning and testing endoscopes by injecting pressurized air into the sheath and pressurized air and washing liquid into the ducts. A washing chamber is provided which contains retractable cages to hold the endoscopes during cleaning and testing. This process includes washing, disinfecting, final rinsing with purified water, and air drying the ducts of a tubular article. A number of filters are involved in this system, and this system is not designed for sterilization.
U.S. Pat. No. 4,744,951 to Cummings et al. discloses a two-chambered system which provides hydrogen peroxide in vapor form for use in sterilization processes. The sterilant is initially vaporized in one chamber and then applied to the object to be sanitized in another single sterilizing chamber, thereby producing a concentrated hydrogen peroxide vapor which is relatively more effective. The sterilization processes are designed for furnishing concentrated hydrogen peroxide vapor to interior surfaces of articles having a tortuous or a narrow path. However, the sterilization processes are ineffective at rapidly sterilizing lumened devices, since they depend on the diffusion of the hydrogen peroxide vapor into the lumen to effect sterilization.
U.S. Pat. No. 4,863,688 to Schmidt et al. discloses a sterilization system consisting of a liquid hydrogen peroxide vaporization chamber and an enclosure for sterilization. The enclosure additionally may hold containers wherein the hydrogen peroxide sterilant vapor does not contact the interior of the containers. This system is designed for controlling the exposure to the hydrogen peroxide vapor. The system is not designed for sterilizing a lumen device.
U.S. Pat. No. 4,943,414, entitled xe2x80x9cMethod for Vapor Sterilization of Articles Having Lumens,xe2x80x9d and issued to Jacobs et al., discloses a process in which a vessel containing a small amount of a vaporizable liquid sterilant solution is attached to a lumen, and the sterilant vaporizes and flows directly into the lumen of the article as the pressure is reduced during the sterilization cycle. This system has the advantage that the water and hydrogen peroxide vapor are pulled through the lumen by the pressure differential that exists, increasing the sterilization rate for lumens, but it has the disadvantage that the vessel needs to be attached to each lumen to be sterilized.
U.S. Pat. Nos. 4,937,046, 5,118,471 and 5,227,132 to Anderson et al. each disclose a sterilization system which uses ethylene oxide gas for sanitation purposes. The gas is initially in a small first enclosure and thereafter slowly permeates into a second enclosure where the objects to be sterilized are located. A medium is then introduced into the second enclosure to flush out the sterilizing gas into a third enclosure containing the second enclosure. An exhaust system then exhausts the sterilant gas and air from the third enclosure. These systems also have the disadvantage of relying on the diffusion of the sterilant vapor to effect sterilization and hence are not suitable for rapidly sterilizing lumened devices.
U.S. Pat. No. 5,122,344 to Schmoegner discloses a chemical sterilizer system for sterilizing items by vaporizing a liquid chemical sterilant in a sterilizing chamber. Pre-evacuation of the sterilizer chamber enhances the sterilizing activity. Sterilant is injected into the sterilizer chamber from a second prefilled shot chamber. This system also relies upon diffusion of sterilant vapor to effect sterilization and is also not suitable for rapidly sterilizing lumened devices.
U.S. Pat. No. 5,266,275 to Faddis discloses a sterilization system for disinfecting instruments. The sterilization system contains a primary sterilization chamber and a secondary safety chamber. The secondary safety chamber provides for sensing and venting to a destruction chamber any sterilization agent that is released from the primary sterilization chamber. This system, as in other systems, also relies upon diffusion of sterilant vapor to effect sterilization and is also not suitable for rapidly sterilizing lumened devices.
In U.S. Pat. Nos. 5,492,672 and 5,556,607 to Childers et al, there is disclosed a process and apparatus respectively for sterilizing narrow lumens. This process and apparatus uses a multicomponent sterilant vapor and requires successive alternating periods of flow of sterilant vapor and discontinuance of such flow. A complex apparatus is used to accomplish the method. Additionally, the process and apparatus of ""672 and ""607 require maintaining the pressure in the sterilization chamber at a predetermined subatmospheric pressure.
In U.S. Pat. No. 5,527,508 to Childers et al., a method of enhancing the penetration of low vapor pressure chemical vapor sterilants into the apertures and openings of complex objects is disclosed. The method repeatedly introduces air or an inert gas into the closed sterilization chamber in an amount effective to raise the pressure to a subatmospheric pressure to drive the diffused sterilant vapor further into the article to achieve sterilization. The ""508, ""672 and ""607 Childers inventions are similar in that all three require repeated pulsations of sterilant vapor flow and maintenance of the sterilization chamber pressure at a predetermined subatmospheric pressure.
One disadvantage of the cleaning/sterilizing or cleaning/disinfecting systems of the prior art as discussed above is that, after the device is sterilized or disinfected and before it is dried, the device has to be rinsed with purified water to remove disinfectant or sterilant residues. A so-called bacteria filter is usually used to filter the water to remove particulates and bacteria. Typically, a two-stage filtering system is utilized, for example, a first stage has a 2-5 micron filter and a second stage has a 0.1-0.2 micron filter. However, virus can be smaller than 0.1 micron. This means the virus can penetrate the filtering system recontaminating the sterilized device in the final rinsing process. Another problem associated with the use of a bacteria filter is that bacteria can form biofilms in the filter which are difficult to sterilize and, thus, become a new potential source of contamination.
In consideration of the foregoing, no simple, safe, effective method of cleaning, sterilizing or disinfecting, drying devices with an integrated process and with the sterilizing (or disinfecting) arid drying being conducted simultaneously exists in the prior art. Thus, there remains a need for a simple and effective process and apparatus for efficiently cleaning, sterilizing or disinfecting, and drying medical devices, especially those with long narrow lumnens.
A method, according to the present invention, supports a device during a cycle. The cycle comprises bathing the device in a fluid for the purpose of cleaning, disinfecting or sterilizing. During a first portion of the cycle the device is supported upon a support member within the fluid, the support member having at least a first contact point and a second contact point which are in contact with the device to support the device. During a second portion of the cycle at least a portion of the support member is moved so that at least one of the first and second contact points are out of contact with the device, thereby reducing occlusive contact between the support member and the device during the cycle. The term xe2x80x9cfirst portionxe2x80x9d is not meant to be limited in time sequence to a portion occurring in time prior to the xe2x80x9csecond portionxe2x80x9d but merely to distinguish two separate portions of the cycle. Thus, the first portion may occur after the second portion.
Preferably, during the second portion of the cycle both the first and second contact points are out of contact with the device. Preferably, no portion of the device which is in contact with the support member during the first portion of the cycle contacts the support member during the second portion of the cycle.
In one embodiment the device is within an enclosure having at least a first chamber and a second chamber therein. The device has a lumen and is placed across a first interface between the first chamber and the second chamber so that the device extends between the first and second chambers. The first interface is a portion of the support member. The method further comprises the step of flowing fluid between the first and second chambers through the lumen. Preferably, during one of the first or second portions of the cycle the first interface substantially seals about the device while leaving a flow path across the interface through the lumen. In one alternative, the first interface can be out of contact with the device during the first portion of the cycle and contact the device during the second portion of the cycle in such a fashion as to move the device away from at least one of the first contact point or the second contact point.
The enclosure can comprises a third chamber and a second interface between the second and third chambers with the device located across both the first interface and the second interface and the second interface is a portion of the support member and wherein the first interface is out of contact with the device during a portion of the cycle and in contact with the device during another portion of the cycle and wherein the second interface is out of contact during a portion of the cycle and in contact with the interface during another portion of the cycle. In such case, one way of implementing the method is to put the first interface and second interface out of contact with the device during the first portion of the cycle and in contact with the device during the second portion of the cycle.
An apparatus for cleaning, disinfecting or sterilizing a device, according to the invention, comprises an enclosure having a support member therein for supporting the device. The support member has at least a first contact point and a second contact point. The support member has a first configuration in which the first contact point and second contact point are in contact with the device while it is supported on the support member and a second configuration in which at least one of the first contact point and second contact point are out of contact with the device while the device is supported on the support member. The apparatus further comprises a mechanism for moving the support member between the first and second configurations.
Preferably, the second configuration comprises both the first and second contact points being out of contact with the device. Preferably, no portion of the device which contacts the support member in its first configuration contacts the support member in its second configuration.
In one aspect of the invention, the enclosure has at least a first chamber and a second chamber therein, and the device has a lumen and is placeable across a first interface between the first chamber and the second chamber so that the device extends between the first and second chambers. The first interface is a portion of the support member. Preferably, one of the first or second configurations comprises the first interface substantially sealing about the device while leaving a flow path across the interface through the lumen. Preferably, the other of the first or second configurations comprises the first interface being out of contact with the device and when the first interface contacts the device it moves the device away from at least one of the first and second contact points.
In one aspect of the invention, the enclosure comprises a third chamber and a second interface between the second and third chambers with the device located across both the first interface and the second interface. The second interface is a portion of the support member. Preferably, the first interface and second interfaces are in contact with the device during one of the first or second configurations and out of contact with the device during the other of the first or second configurations. Preferably, when the first and second interfaces are in contact with the device no other part of the support member which contacts the device in the other of the first and second configurations contacts the device.
In one aspect of the invention, the mechanism for moving the support member between its first and second configurations comprises a mechanism for moving the first interface into or out of contact with the device.